Corner pivot slide mounts for a slide projector



Jan. 20, 1970 J. H. EAGLE 3,490,840

CORNER PIVOT SLIDE MOUNTS FOR A SLIDE PROJECTOR S Sheets-Sheet 1 FiledSept. 12. 1967 FIG. I

JOHN H. EAGLE INVENTOR.

ATTORNEYS.

J. H. EAGLE Jan. 20, 1970 CORNER PIVOT SLIDE MOUNTS FOR A SLIDEPROJECTOR 3 Sheets-Sheet 2 Filed Sept. 12, 1967 JOHN H. EAGLE INVENTOR.

ATTORNEY Jan. 20, 1970 J. H. EAGLE CORNER PIVOT SLIDE MOUNTS FOR A SLIDEPROJECTOR 3 Sheets-Sheet 5 Filed Sept. 12, 1967 R u E 4. am AWE 7% R EvM nm N @h N .Wm H I. 4 W 0 I, M ,C. M 4 J a. w

United States Patent 3,490,840 CORNER PIVOT SLIDE MOUNTS FOR A SLIDEPROJECTOR John H. Eagle, Rochester, N.Y., assignor to Eastman KodakCompany, Rochester, N.Y., a corporation of New Jersey Filed Sept. 12,1967, Ser. No. 667,157 Int. Cl. G03b 21/00 US. Cl. 353120 8 ClaimsABSTRACT OF THE DISCLOSURE A plurality of generally square slide mountsare assembled in stacked relation to form a slide pack which is heldtogether by a pivot rod extending through the mounts at one corner ofthe pack so that each mount can be pivoted about the rod independentlyof the others. To display the individual slides, the pack is supportedin a projector including means for incrementally moving the entire packand successively rotating the slide mounts about the pivot rod to locateeach slide, in turn, at a predetermined projection position aligned withthe optical system of the projector.

BACKGROUND OF THE INVENTION The present invention relates to imagerecording slides of the type comprising a slide mount supporting a pieceof transparent image bearing film or the like, and more particularly tomeans for assembling a plurality of such slides into a unitary pack.

In order to facilitate displaying a plurality of slides in apredetermined sequence, it is well known to store such slides in amagazine adapted to be received by a projector which includes means forsequentially removing the slides from the magazine, projecting them, andreturning them in the same order to the same magazine or to anothersimilar magazine. To prevent the slides from being accidentally removedfrom the magazine or accidentally rearranged therein, it is also knownto pivotally attach each slide to the magazine by means of acorresponding lateral arm, which may be formed either integrally withthe slide or as a separate member adapted to be attached thereto,whereby each slide can be pivoted independently out of the magazine andinto projection position while remaining positively connected to themagazine structure.

Although various forms of such previously known slide magazines havebeen widely adopted, any such arrangement inherently requires a separaterelatively expensive magazine unit for use with each set of slides.Furthermore, the space required to store or transport the slides per seis increased by the magazine structure, in some cases to the extent thatan otherwise superior type of magazine and projector combination may beimpractical for use by travelling lecturers'and the like, to whomcompactness for purposes of convenient portability is a majorconsideration.

The present invention provides the functional advantages of theabove-described types of slide magazines, including preventingaccidental removal or rearrangement of the slides, while at the sametime substantially eliminating both the additional expense of theseparate magazine structure and also the bulkiness associated therewith.

SUMMARY OF THE INVENTION This invention includes within its scope theforming of individual slide mounts of relatively rigid somewhatresilient material, preferably plastic, and by stacking the slides alonga pivot rod extending through aligned pivot holes in the individualslides at one corner of the slide stack. The pivot rod is provided atopposite ends of the stack with flanges of greater diameter than thepivot holes and thereby retains a predetermined number of slides inadjacent relation while allowing them to rotate independently in fanlikefashion about the pivot rod.

In one embodiment of the invention, the pivot rod is separable to allowremoval of one of its end flanges so that the rod can be insertedthrough closed circular pivot holes in the slide mounts comprising aslide pack, whereupon the removable flange member is replaced on the rodto prevent accidental separation of the assembled slide pack. In anotherembodiment, the pivot rod is a one-piece member flanged at both ends,with the pivot hole of each slide mount including a restricted openingcommunicating with the adjacent exterior corner of the mount, wherebythe rod can be forced laterally into or out of the pivot hole of eachslide by distorting the somewhat resilient slide mount material toenable the rod to pass laterally through the restricted opening.

To facilitate proper obverse stacking of the slides as the slide pack isassembled and also to insure correct orientation of the pack relative tothe slide changing mechanism of a projector in which it is installed,the slides are also provided with similarly disposed edge notches orother edge discontinuities which are located in non-symmetrical relationto the slides so that they are in alignment along an edge of the packonly if all of the slides are similarly obversely oriented.

From the foregoing it will be recognized that when a predeterminednumber of the slides are assembled properly on the pivot rod, theresulting slide pack comprises a unitary assembly which can be stored ortransported conveniently and compactly, without danger of disturbing theslide sequence.

To display the slides, the slide pack is loaded into a correspondingprojector with the pack oriented in proper obverse relation to themachine and with the pivot rod at a predetermined position. Since theslide changing mechanism cannot operate properly and might damage theslides unless the pack is so oriented in the projector, theabove-mentioned edge notches or the like cooperate with a mating memberin the projector to insure that the pack cannot be removed intoengageable relation with the slide changing mechanism if it is notinstalled correctly. As the projector is operated, the slide pack ismoved unitarily along the axis of the pivot rod by incrementscorresponding to the thickness of the slides, as each slide, in turn, isengaged by the slide changing mechanism and thereby rotated about thepivot rod into a stationary gate structure adapted to support it at apredetermined projection position aligned with the optical system of theprojec tor. After each slide has been displayed while supported in thegate structure, it is again rotated about the pivot rod to return it toits former position in the pack, whereupon the pack is movedsufliciently to align the next slide with the gate so that it can besimilarly rotated into projection position. After this procedure hasbeen repeated to display all of the slides in the pack, the pack isremoved from the projector, with all of the slides thereof stillpivotally retained in their original order along the pivot rod, so thatthe pack can be stored and displayed again without any reassembly of thepack or risk of accidental rearrangement of the slides.

Various means for practicing the invention and other I advantagesafforded thereby will be apparent from the following detaileddescription of illustrative embodiments thereof, reference being made tothe accompanying drawings in which like reference numerals refer to likeelements.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of avertically positioned slide pack according to the present invention,showing one of the slides pivoted out of alignment with the other slidescomprising the pack;

FIG. 2 is a partially exploded view of the slide pack shown in FIG. 1,disposed in a horizontal position, illustrating the individualcomponents comprising one of the slides and the manner in which theslides are pivotally joined by the pivot rod;

FIG. 3 is an enlarged perspective view of a pivot rod and portions oftwo corresponding slides according to an alternate embodiment of theinvention, showing the manner in which the slides are laterallyinstalled on and removed from the one-piece pivot rod to assemble orrearrange a slide pack;

FIG. 4 is a partial elevational view of the pivot corner of a slidecomprising a variation of the embodiment shown in FIG. 3, depicting incross section the pivot rod received within the pivot hole;

FIG. 5 corresponds to FIG. 4 and shows the manner in which portions ofthe slide adjacent the pivot hole are resiliently deformed to allow thepivot rod to be received laterally into the pivot hole;

FIG. 6 is a reduced perspective rear view of a preferred embodiment of aslide projector adapted to receive and display a slide pack according tothe invention;

FIG. 7 is a perspective rear view of the internal mechanism of theprojector shown in FIG. 6, with the various elements thereof positionedto receive a slide pack loaded into the projector as shown in brokenlines;

FIG. 8 corresponds to FIG. 7 and shows the respective positions of theprojector components and the slides comprising a slide pack therein whenone of such slides is positioned in the projector gate for projection ofan image thereof;

FIG. 9 is an end elevational view corresponding to a portion of FIG. 8,illustrating more clearly the manner in which one of the slides in thepack is pivoted into projection position; and

FIG. 10 is an enlarged partial side elevational view of a portion of theescapement mechanism shown in FIGS. 8 and 9, which controls the movementof the slide pack to laterally align successive slides thereof with theprojector gate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIGS. 1 and2 of the drawings, it will be seen that a slide pack 10 according to thepresent invention comprises a plurality of substantially square slides11 provided with rounded corners and pivotally held together by a pivotrod 12 so that each slide can pivot about the rod independently of theothers. As shown in FIG. 2, which illustrates one of the slides inunassembled form to depict its component parts, each slide includes aslide mount comprising a pair of substantially similar generally squareslide mount members 13, each of which is provided with a square imageaperture 14, a corner hole 15, and an edge notch 16 located off-centeralong one edge of the mount member. To assemble each slide, the twomount members are positioned as shown in FIG. 2 with their respectiveapertures 14, holes 15 and edge notches 16 in opposed alignment witheach other. An image bearing transparency member 17, comprising a pieceof photographic film or similar transparent material, is provided withan edge perforation 18 in predetermined non-symmetrical relation to theimage recorded on the central image area thereof and is adapted to bepositioned in recess 19 in one of the mount members when oriented sothat the metering perforation can receive fixed projection 20 extendinginto the recess; thereby insuring a predetermined mode of orientationbetween the slide mount and the image recorded on the transparencymember. The mount members are then placed together and cemented orpermanently joined in some other manner along their contacting surfaces,with the marginal portion of the transparency member sandwiched betweenthe mount members within the recess and with the aligned holes,apertures and notches cooperating to define corresponding openings inthe assembled slide mount. Thus, the transparency member is permanentlymounted in flat relation in the assembled slide mount with its centralimage area aligned with apertures 14 and offset diagonally relative tothe mount member toward the corner thereof opposite the corner pivothole defined by the aligned corner holes 15 in the two mount members.

It should be understood that although the slide mounts preferably areformed of plastic material, other materials could also be used for thatpurpose, and, similarly, that the invention could be practiced withslide mounts other than those comprising a two-piece laminated assembly.

To assemble the illustrated slide pack, ten slides are stacked in anydesired sequence with their edge notches and their corner pivot holes inalignment, so that the image areas of the slide transparencies are alloriented in the same sense. The pivot rod 12 is then fed through thealigned corner pivot holes to locate its end flange 21 against the endface of the slide at the adjacent end of the pack, whereupon theremovable flange member 22 is attached to the opposite end of the rod byscrewing threaded shank 23 into a mating threaded hole 24 in the pivotrod. To insure free movement of the slides about the pivot rod, thelength of the rod is such that when ten slides of uniform predeterminedthickness are stacked thereon, the removable flange can be screwedtightly onto the rod to maintain the slides in close adjacency to oneanother without actually squeezing them together. It should be obvious,of course, that a slide pack need not necessarily include ten slides, asillustrated, but that the pivot rod should correspond in length to thenumber of slides assembled together to retain them in adjacentfaceto-face contact.

FIG. 3 shows an alternate embodiment of the pivot rod and corner pivothole structure of a slide pack comprising slide mounts otherwiseidentical to those previously described. In this embodiment, the pivotrod 25 is a onepiece tubular member of predetermined length permanentlyflanged at both ends and adapted to be received in the circular portions26 of corner pivot holes 27 extending through slide mounts 28, which areformed of sufliciently resilient material to allow the rod to be forcedlaterally into the pivot holes through restricted corner openings 29 byexpanding the openings to allow passage of the rod therethrough. Thisarrangement, therefore, not only simplifies the construction of thepivot rod, but also facilitates assembling and editing the slide pack byallowing any slide to be removed and replaced or repositioned withoutremoving the other slides from the rod.

FIGS. 4 and 5 show a modification of the pivot hole portion of the slidemount illustrated by FIG. 3, whereby a pair of elongate slots 30 areprovided in each slide mount 31, extending from the circular portions 32of the pivot hole in parallel relation to the adjacent edge surfaces ofthe slide mount. When the slide is attached to the previously describedtubular pivot rod 25, the rod is received in the circular portions ofthe hole, as shown in FIG. 4, beyond the restricted corner opening 33defined between the opposed ends of elongate arms 34, which extend alongcorresponding edges of the slide mount adjacent slots 30. As the rod isforced laterally into or out of the pivot hole, as depicted in FIG. 5,the corner opening is expanded by flexing the arms outwardly.Accordingly, as compared to the structure shown in FIG. 3, this cornerconfiguration substantially reduces the distortional stress on the mountas the rod is installed or removed and enables such operation to beperformed with less force, by allowing the arms to flex throughout theirlengths rather than concentrating such flexure immediately adjacent thecorner opening.

FIG. 6 shows the external appearance of an illustrative slide projectoradapted to receive a slide pack of the type described above and todisplay, in sequence, the ten slides of which the pack is comprised. Ahousing 35 substantially encloses the internal components of theprojector and is provided with an opening 36 through which a slide packcan be loaded into or removed from the unit. A lens tube 37 ispositioned along a horizontal axis extending above the slide pack and issupported by the housing, which is also provided with slots 38 and 39adapt ed respectively to allow manual sliding movement of slide changinghandle 41 and transfer knob 42.

The principal internal components of the projector unit are illustratedby FIG. 7 with the movable elements thereof shown positioned to receivea slide pack to load the projector.

Directly below opening 36 in the housing, a channel member 43 issupported on an internal base plate 44, by spacer sleevs 45. Theupwardly bent side flanges 46 and 47 of the channel member are spacedapart by a distance corresponding to the width of the slides, and serveto support slide transport member 48, which is slidably mounted toflange 46 by pins 49 extending through elongate slot 51 in side plate 52of the transport member and by corresponding means mounting the oppositeside plate 53 to flange 47. The two side plates of the transport memberare joined by a cross bar 54 and by a vertical transverse plate 55extending downwardly between the flanges. A second vertical transverseplate 56, which also extends downwardly between the flanges, issupported behind plate '55 by slotted support ears 57 bent into grippingengagement with the cross bar, with the facing surfaces of the twotransverse plates spaced apart by a distance corresponding to thethickness of a slide pack. As shown at 58, an extensible coil spring isconnected between the cross bar and an upright leg 59 on the channelmember to urge the transport member toward its illustrated rearwardmostposition defined by the engagement of the forward end of slot 51 withthe adjacent pin 49. In this position, the transverse plates are alignedwith opening 36 in the housing, to enable a slide pack to be insertedinto the projector through that opening and between the rounded upperedges of the transverse plates, so that the pack is supported forwardlyand rearwardly in immovable relation to the transport member by theopposed flat surfaces of the transverse plates, and laterally betweenthe side flanges of the channel members, as shown in broken lines inFIG. 7.

Toward the front end of channel member 43, a pair of rigid verticalsupport members 61 and 62 are located at opposite sides of a verticalopening 63 in side flange 47, such opening being defined betweenoutwardly bent flange ears 64 and 65 which are spaced apart by adistance only slightly greater than the thickness of one of the slidemounts. At their upper ends, the vertical support members are providedrespectively with parallel gate members 66 and 67, supported verticallyat right angles to the axis of the projectors optical system,represented by objective lens systems 68 and projection lamp 69. Thegate members are spaced apart by a distance corresponding to thethickness of a single slide and are provided with aligned apertures 71and 72, concentric with the optical axis of lens system 68. Thus, when aslide is received between the gate members with its transparency memberaligned with the gate apertures, the image-bearing surface of thetransparency member will be located along the optical axis in apredetermined position at which a sharp image of that surface can befocused on a projection screen by the lens system.

When the slide pack has been loaded into the projector, it is movedmanually along the channel member toward the front of the projector bysliding the transport member forwardly against the influence of spring58 by means of transport knob 42, which is attached to the transportmember by a vertical leg 73 extending upwardly from side plate 52. Ifthe slide pack is oriented properly in the projector, the edge notches16 along one side of the pack will be aligned with opening 74 intransverse plate 55 and with an inwardly facing lip 75 extending alongthe top edge of the forward portion of side flange 46, whereby the lipwill be received in the aligned edge notches without interfering withsuch movement. However, if the pack is not so oriented, the lip will beengaged by the corresponding edge surface of the forwardmost slidemount, thereby blocking further movement of the slide pack before it isin a position accessible to the slide changing mechanism and alertingthe operator to remove the pack and reposition it correctly.

As the properly oriented slide pack is moved forwardly in the projectorby the transport member, an escapement rack 76 along the lower edge ofside plate 52 moves into vertical alignment with pallet teeth 77 and 78of pallet member 79. The pallet member is supported on the base platefor rocking pivotal movement by brackets 81 and pivot shaft 82 and isprovided with a release arm 83 biased upwardly by a weak coil spring 84to urge pallet tooth 78 toward engagement either with the smooth loweredge surface 85 of side plate 52 or with the escapement rack, dependingon the position of the transport member. The forward end of the releasearmv includes a cam follower ear 86 located below cam lip 87 along thelower edge of slide rotating member 88, which is supported forhorizontal sliding movement on vertical support plate 89 by pins 91extending through slot 92. As will be eX- plained below in greaterdetail, the cam lip includes a horizontal lower portion 93 and a slopedend portion 94, the latter being located above ear 86 when the sliderotating member is in the position shown in FIG. 7.

Each tooth of the escapement rack is exactly as wide as the thickness ofone of the slide mounts and, as best shown by FIG. 10, each rack toothincludes a vertical rear face and sloped front face, whereas the ends ofthe pallet teeth include similarly sloped rear faces and vertican frontfaces. Accordingly, as the rack moves forwardly, the front pallet tooth78 is cammed downwardly by each successive rack tooth against theresistance of spring 84 as the other pallet tooth enters the spacebetween the pair of rack teeth immediately above it, whereby the palletmember simply oscillates about its pivot shaft without blocking theforward movement of the transport member. When the transport memberreaches its extreme forward position, defined by the abutment of therearward end of slot 51 against rearward pin 48, it is latched in thatposition against the rearward force of springs 58, by the engagement ofpallet tooth 78 with the rearward surface of the adjacent rack tooth. Inthis position, the rearward slide in the slide pack is positionedslightly ahead of the slide receiving space between the gate members andin similar relation to the slide rotating member, which is centrallysupported between the planes defined by the spaced confronting surfacesof the gate members.

To display the first slide, i.e. the rearwardmost slide in the pack,slide changing handle 41 is moved manually along slot 38 toward theoptical axis of the projector to move the slide rotating member in thesame direction. During the initial stage of such movement, and beforethe slide rotating member comes into engageable relation to the slidepack, the cam lip thereon is displaced sufficiently to cam ear 86downwardly into contact with lower portion 93 of the lip, therebyrocking the pallet member to the position shown in FIG. 8 and in sOlidlines in FIG. 10. Such movement of the pallet member disengages thefront pallet tooth 78 from the rack as the rear pallet tooth 77 entersthe space between the two rack teeth positioned above it. Therefore, asthe front pallet tooth releases the rack, spring 58 moves the transfermember rearwardly through a distance less than the width of a rack toothto a position defined by the engagement of the rear pallet tooth withthe vertical face of the adjacent rack tooth, such movement beingsufficient to move the first slide into accurate lateral alignment withthe gate and with the slide rotating member.

As the movement of the slide rotating member continues, the adjacentedge of the slide mount aligned with the slide rotating member isengaged below the pivot rod by the rounded end portion 95 of a thinhorizontal slide rotating arm 96 projecting laterally from that member.Accordingly, as the slide rotating member completes its movement to theposition shown in FIG. 8, the slide mount engaged by arm 96 is therebymoved rotatively about the pivot rod between flange ears 64 and 65 andvertical support members 61 and 62 and into projection position betweengate members 66 and 67. Since opening 63 in slide flange 47 of thechannel member is aligned with and only slightly wider than thethickness of the slide mount engaged by arm 96, it is apparent that suchrotational movement of that slide does not disturb the positions of theother slides in the pack, which are restrained against similar movementby the slide flanges of the channel member.

When the slide rotating arm has been moved to the end of its movementpath established by the abutment of the opposite end of slot 92 with theadjacent pin 91, the horizontal upper edge surface 97 of the arm servesto support the raised slide with the transparency member thereofaccurately aligned with the gate apertures, as is most clearlyillustrated by FIG. 9. Thus, the slide is positioned properly forprojection of a focused image of its image bearing surface and willremain so positioned until arm 96 is subsequently withdrawn from theslide pack.

As indicated by numeral 98, a bifurcated lever is attached to gatemember 67 by a pin 99 and is pivotally biased by a spring 101 toward aposition established by the engagement of ear 102 with edge surface 103of that gate member, in which position nose portion 104 of the lever islocated between the two gate members just above the slide pack.Therefore, as the slide is rotated into projection position, it engagesthe nose portion of the lever and pivots the lever to the position shownin FIG. 8 against the influence of spring 101, so that the leverlaterally exerts a resilient pivotal force on the slide, tending torotate it back to its initial position in the pack.

After the slide in the gate has been displayed, handle 41 is movedmanually back toward its initial position to withdraw slide rotating arm96 from the slide pack so that the slide mount supported thereby canrotate back to its previous position in the pack under the influence ofits own weight and the supplemental force of spring biased lever 98.Until such return movement of the slide rotating member has withdrawnthe arm sufiiciently to allow the slide mount to be rotated back intothe pack, the lower portion 93 of cam lip 87 continues to depress ear 86of the pallet member to prevent rearward movement of the transportmember by spring 58. During the final stage of such return movement ofthe arm, however, after the slide is returned to the pack, the slopedend portion 94 of the cam lip moves into alignment with the cam followerear and allows the pallet member to be rocked back to the position shownin FIG. 7 and in broken lines in FIG. 10. Accordingly, pallet tooth 77disengages the rack and allows the transport member to move rearwardlyby somewhat less than the distance required to bring the succeedingslide into lateral alignment with the gate, before again being blockedby the engagement of pallet tooth 78 with the vertical edge of theadjacent rack tooth. At this stage of the operation of the projector,all of its movable components have been restored to the respectivepositions which they assumed just prior to rotation of the first slideinto projection position, except that the transport member is nowpositioned rearwardly of its former position by the width of one racktooth so that operation of the slide rotating member will now move thesucceeding slide into the gate. Thus, it

should be apparent that each successive operation of the slide changinghandle will cause a succeeding slide to be displayed. When the lastavailable slide has been rotated back into the pack, the front toothalong the escapement rack will have moved beyond pallet tooth 78 toallow the transport member to be returned by spring 58 to the positionshown in FIG. 7, so that the pack can be removed from the unit andanother pack installed therein.

Although the foregoing description relates to specific embodiments ofthe invention, it is obvious that variations and modifications thereofcan be effected within the spirit and scope of the invention.Accordingly, the present disclosure is to be considered as illustrativeand not as limiting the scope of the invention which is defined by thefollowing claims.

I claim:

1. A slide pack comprising:

a plurality of structurally identical substantially rectangular fiatslide mounts,

means defining a generally rectangular image aperture in each of saidmounts,

means defining in each of said mounts a generally circular pivot holeadjacent a corner of said mount and spaced from the said aperturetherein,

an elongate pivot rod extending through said pivot holes in saidslide,mounts to support said slide mounts for independent pivotalmovement about said pivot rod,

each of said mounts further defining an opening extending between saidpivot hole and the adjacent corner of said slide mount, said openingbeing narrower than the transverse dimension of said pivot rod, saidslide mount being formed of suflficieutly resilient material to allowlateral movement of said pivot rod into said pivot hole through saidopening by resiliently enlarging said opening to accommodate said rod,and

flange members at opposite ends of said pivot rod adapted to retain saidslide mounts on said pivot rod in independently pivotable relation toone another.

2. A slide mount comprising:

a generally rectangular flat member formed of resiliently deformablematerial,

means defining in said member a generally rectangular image aperture,

means for supporting a transparency member in said aperture,

means adjacent a corner of said member defining therein a pivot holeincluding circular internal edge surfaces, and

means defining an opening at the adjacent exterior corner of said memberextending diagonally of said member and merging with said pivot hole,said opening being narrower than the diameter of the circle defined bysaid circular internal edge surfaces of said pivot hole.

3. The invention defined by claim 2 including means defining a notchlocated along one edge of said member beyond the center point of saidedge.

4. The invention defined by claim 2 including means defining an elongateslot merging with said pivot hole and extending away from said opening.

5. The invention defined by claim 4 in which said elongate slot isgenerally parallel to an adjacent edge surface of said slide mount.

6. An image recording slide comprising:

a generally rectangular fiat slide mount member formed of resilientlydeformable material,

means defining in said mount member a generally rectangular imageaperture,

means adjacent a corner of said mount member defining therein a pivothole,

means defining an opening narrower than said pivot hole extendingdiagonally therefrom to the adjacent exterior corner of said mountmember,

means defining along an exterior edge surface of said mount member aphysically detectable discontinuity located in non-symmetrical relationto said mount member,

an image bearing transparency member, and

means for supporting said transparency member in said aperture with theimage thereof in a predetermined mode of orientation relative to saiddiscontinuity.

7, A slide pack comprising a plurality of slides according to claim 6and including an elongate pivot rod member extending through therespective pivot holes of said plurality of slides to support saidslides in mutually adjacent relation for independent pivotal movementabout said pivot rod.

8. A slide mount adapted to support a rectangular transparency memberprovided with a perforation adjacent one edge thereof in non-symmetricalpredetermined relation to an image recording surface area of saidtransparency member, said slide mount comprising:

a generally rectangular flat mounting member including means definingtherein an aperture smaller than said transparency member,

means defining about the periphery of said aperture a shallow recesscorresponding in lateral dimensions to the lateral dimensions of saidtransparency member,

a fixed projection extending from said mounting member into said recessand adapted to mate with said perforation when said transparency memberis received in said recess in a predetermined mode of orientationrelative to said mounting member and to engage an imperforate area ofsaid transparency References Cited UNITED STATES PATENTS Weeks 40-152Shuss 12923 Pierce 2()774 Whittum 40-106.1 Winnemann 353120 HARRY N.HAROIAN, Primary Examiner US. Cl. X.R.

